The main parameters in detecting raindrop size distribution are overviewed, and the traditional measuring methods are discussed separately. Most of them possess the shortcomings of low measurement precision, big error, workload and poor real-time response. New type measurement raindrops spectrum tool-laser disdropmeter are developed, and the measurement principle of disdropmeter are analyzed in detail. Compared to traditional measurements, the virtues of disdropmeter in detecting raindrop size distribution are pointed out. The applications of disdropmeter, such as raindrop size distribution, rainfall measurement and the correction of weather radar et al are given. The developments of laser disdrometer technology at home and abroad are displayed. The research work progress on laser disdrometer of the Key Laboratory of Atmospheric Composition and Optical Radiation, CAS, is introduced. The experiments carried out with laser disdrometer in recent years are simply discussed.